1. Field of the Invention
The present invention relates to collapsible shelters and tents having sheet material walls supported by a collapsible frame. The present invention provides, among other things, an improved collapsible shelter or tent having a frame locking mechanism.
2. Background of the Invention
Collapsible tents, such as umbrella tents, are well known in the art. The term "umbrella tent" is commonly used in the trade because the frames for'such tents can be erected and collapsed in much the same manner as an umbrella. Some exemplary collapsible tents are shown in, for example, U.S. Pat. Nos.: 5,230,358 (Forell); 4,945,936 (D. Surrendi); 4,202,363 (Watts et al.); 3,929,146 (Maiken); and 2,771,087 (Simonson).
U.S. Pat. No. 5,230,358 shows a foldable tent and frame therefor that includes a number of complex drive mechanisms to move upper and lower spiders 14 and 16, respectively, toward and away from one another to erect and collapse the tent frame. The drive mechanisms also include a locking mechanism for securing the spider assembly in an erected condition.
U.S. Pat. No. 4,945,936 shows a collapsible tent having a frame with an upper clevis member 10 and a lower clevis member 11 that are manually moved towards and away from one another, without a complex drive mechanism, to erect and collapse the tent. The '936 tent does not contain, however, a separate locking mechanism to lock the upper and lower clevis members together. In order to assemble the tent, the tent is initially in a position like that shown in FIG. 2. The lower clevis member 11 is then forced up towards the upper clevis member 10. The structure of the tent creates a force resisting upward movement of the lower clevis member 11 towards the upper clevis member 10 until the radial brace members 28 become generally horizontal. Thereafter, the force on the lower clevis member 11 actually causes the lower clevis member 11 to move towards the upper clevis member 10. As a result, in an assembled state as shown in FIGS. 1 and 5, wherein the stop member 26 is seated within the recess 15, the tent is self-sustaining and an additional locking mechanism is not included. The '963 patent can collapse, however, upon the application of a modest downward pressure to the top of the upper clevis member when the frame is assembled.
U.S. Pat. No. 4,202,363 shows an umbrella type collapsible shelter having an upper hub 12 and a lower hub 14 that are moved toward one another to erect the shelter. Similar to the '936 device, when the rib members 15 move past the position perpendicular to the vertical center line of the shelter, the resultant upward force on the hub 14 due to the stress in the bowed support members 11 tends to hold the hub 14 proximate to the central hub 12 to maintain the shelter in the erected position. (See col. 4, lines 45, et seq., of the '363 patent.) In addition, the '363 device includes means for preventing inadvertent collapse of the shelter. In particular, the upper hub 12 includes a bore 23 and the lower hub 14 includes a bore 24 aligned with but eccentric to the bore 23. An erecting means 13 (e.g., an elongated rope or rod) extends through the bores 23 and 24. After the structure is assembled, as stated on col. 6, lines 17 et seq., "[t]he second hub 14 is then rotated by about onequarter to about three-eighths of a turn about the axis of the erecting means" which creates a binding action due to the eccentric relationship. The '363 device, however, has a number of drawbacks--for example: a) the means for preventing inadvertent collapse of the hubs 12 and 14 involves hubs which rotate with respect to one another (and with respect to legs or the like attached thereto); b) the means for preventing inadvertent collapse is complex, unreliable, and can create undue stress on parts; c) the '363 involves mounting the shelter fabric within the frame, creating undue exposure and potential damage of the frame structure and creating other deficiencies.
U.S. Pat. No. 2,771,087 shows a portable screen having a locking mechanism that locks together an upper ridge piece 12 and a lower latching block 24. The locking mechanism of the '087 device also contains a number of drawbacks. In the '087 device, the latching block 24 has an upper cap member 30 with a coil spring 40 that biases loop portions 40 outwardly. The ridge piece 12 includes a central bore 20 that receives the cap member 30. A flexible element 44 is used to pull the cap member 30 vertically through the bore 20 of a ridge piece 12 to lock the latching block 24 to the ridge piece 12 once the loop portions 36 are seated above the screen 54 to lock the device. The drawbacks of the '087 device include, for example, that the locking mechanism can be: a) disadvantageously exposed to the environment; b) inconvenient since disassembly should be initiated from outside of the shelter; and c) undesirable because it involves mounting the frame outside of the screen 54 which reduces the design options of the device.
There remains a need in the art for the continued improvement of collapsible shelters and tents and, for example, for a collapsible shelter or tent having an improved means for locking a frame thereof in an assembled state.